The invention relates to dump vehicles which are used for transporting sand, gravel or other loose materials which are relatively heavy. Specialized vehicles for this purpose are necessary due to the many varied materials which must be carried and the many varying conditions under which the vehicles must operate. The vehicles are primarily used in general construction work where the conveying of sand, concrete, rocks, earth, and such other loose materials is often required. Some uses of the transported material, such as the spreading of earth or gravel, require the use of a belly dump vehicle. These are vehicles which are equipped to transport a load over a distance and to empty the load through the bottom or belly of the hopper carrying the load. Other uses, such as the placing of large amounts of material in particular locations, require the use of end dump vehicles. End dump vehicles are dump vehicles which empty the contents of the bed by raising the front end of the bed and letting the contents slide through the tail gate or over the end of the bed. Because of the completely different structure normally attendant to end dump type vehicles and belly dump type vehicles, there are some tasks which each type of vehicle simply cannot economically perform. Construction companies normally own, rent or otherwise operate a plurality of different specialized dump vehicles in order to accomplish the different tasks required in construction work. Alternatively, construction companies sometimes use dump vehicles for uses for which they have not been primarily designed. It is, for example, a common occurrence to see an end dump vehicle being used to lay long strips of earth or gravel, rather than the more efficient belly dump vehicle. This is due to the fact that such equipment must be continually used to justify their purchase cost even if such use is not always the one for which they were designed.
Two different catagories of dump vehicles have been developed in response to these conditions. First, extremely specialized dump vehicles are purchased and used by large companies which can be assured of sufficient demand for the specialized dump vehicle to insure that the specialized dump vehicle will only be used for one specific task. There vehicles have many refinements and are extremely efficient at the jobs for which they were designed. A second type of dump vehicle which has been developed are dump vehicles which are designed primarily for a single type of use, but are also intentionally designed to be at least marginally efficient for other types of uses. An example of this type of vehicle is an end dump truck which is useful in the laying of layers of earth as described above.
The small construction company or the individual who wishes to purchase only one or only a few dump vehicles which will necessarily be used for a multitude of purposes is put at an extreme disadvantage. Present day dump vehicles confine his choice to either an end dump type vehicle, which will necessarily be inefficient in the performance of belly dump type vehicle tasks, or the purchase of a belly type dump vehicle, which will be inefficient in the performance of end dump type vehicle tasks. Therefore, a dump vehicle is needed which can be efficiently operated in both belly dump and end dump modes.
An additional problem which current designs of end dump vehicles do not satisfactorily solve is the propensity of end dump vehicles to capsize if used upon soft or uneven ground. Most end dump vehicles operate by raising the front end of the bed so that the contents will slide out or over a rear end of the bed. Due to structural design, which will be discussed below, this involves placing the major portion of the weight of the bed and its contents upon the rear wheels. As the bed is rotated over the rear wheels, any slight angular deviation of the ground from the ideal horizontal surface is communicated to the upraised bed. The longer the bed, the greater the effect of the angular deviation thereon and the more unstable the entire truck. Soft or marshy ground can add to the problem. A means is needed to stabilize end dump vehicles during the process of dumping.